We introduce a new solution concept to problems with
externalities, which is the first in the literature to take
into account economic, regulatory and physical stability
aspects of network problems in the very same model. A new
class of cooperative games is defined where the worth of a
coalition depends on the behavior of other players and on the
state of nature as well. We allow for coalitions to form both
before and after the resolution of uncertainty, hence
agreements must be stable against both types of deviations.
The appropriate extension of the classical core concept, the
Sustainable Core, is defined for this new setup to test the
stability of allocations in such a complex environment.
A prominent application, a game of consumers and generators
on an electrical energy transmission network is examined in
details, where the power in- and outlets of the nodes have to
be determined in a way, that if any line instantaneously
fails, none of the remaining lines may be overloaded. We show
that fulfilling this safety requirement in a mutually
acceptable way can be achieved by choosing an element in the
Sustainable Core.